1. Field of the Invention
The present invention relates to an image forming apparatus and an image formation system.
2. Description of Related Art
In general, an electrophotographic image forming apparatus (such as a printer, a copy machine, and a fax machine) is configured to irradiate (expose) a charged photoconductor with (to) laser light based on image data to form an electrostatic latent image on the surface of the photoconductor. The electrostatic latent image is then visualized by supplying toner from a developing device to a photoconductor drum (image carrier) on which the electrostatic latent image is formed, whereby a toner image is formed. Further, the toner image is directly or indirectly transferred to a sheet, and then heat and pressure are applied to the sheet at a fixing nip of a fixing device to form an image on the sheet.
In recent years, image forming apparatuses can provide a high quality image as a result of the trend of digitization, high-definition and the like. Enhancement of image quality has led to approach to utilize electrophotographic-color image forming apparatuses in the print market and photograph market. In this approach, images having no margin at sheet end portions (frameless-printing) have been strongly desired in the fields of graphic art and photograph printing service.
Frameless-printing can be achieved by forming an image which has no margin at the end portions in the first place, or by cutting out the margin of an image after the image is formed together with the margin at the sheet end portions. In electrophotographic image forming apparatuses, when an image having no margin at the end portions is formed, a toner image having a size substantially greater than the sheet size is required to be transferred on the sheet, and as such a transfer member is contaminated with the toner falling outside the sheet size during the transferring process, thus contaminating the rear surface of the sheet. Therefore, the method of cutting the margin of the image is advantageous in view of preventing contamination of the printed image. To cut out the margin of the image, however, a cutting device for cutting out sheet end portions is additionally required.
As such a cutting device, Japanese Patent Application Laid-Open No. 2005-262409 discloses a round blade pair cutter including a first round blade and a second round blade which rotate and mesh with each other in an overlapping manner, in which a sheet is sandwiched by the first round blade and the second round blade and is cut in the sheet movement direction by relatively moving the sheet and the first and second round blades. Further, PTL 1 discloses a configuration including a separation member for separating a cut waste sheet in a predetermined direction.
With the technique disclosed in Japanese Patent Application Laid-Open No. 2005-262409, however, the orientation of the sheet at the time of the cutting changes due to the use of different sheets having different rigidities, the width of the cut waste sheet, and the travelling direction of the cut waste sheet, thus causing a quality problem of the cut surface of sheets, such as a napped cut surface and waviness in the sheet width direction. For example, when a sheet is cut at a position (for example, second round blade position) on the upstream of the nip position where the first round blade and the second round blade mesh with each other, the cut surface of the sheet is napped.